The Seattle Times said the world-record 57.5-foot in diameter drill is scheduled to dig below Seattle next year.
The giant cutter head will be attached to a giant machine that is longer than a football field.
The team at Hitachi-Zosen will test the machine before the Washington State Department of Transportation formally accepts it at a ceremony in December.
Then the drill will be dismantled into 41 sections and shipped to Seattle in March. Drilling of the two-mile tunnel is scheduled to start in June.
Breakthrough is scheduled at South Lake Union by October 2014, with traffic to use the four-lane toll tunnel by the start of 2016.
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